The utility model provides a prevent condensation dehumidifier, including setting up at inside inner sensor of electrical cabinet and the external sensor that sets up cabinet wall outside electrical cabinet, inner sensor and external sensor all connect same heating ventilation control module, heating ventilation control module is connected with the refrigeration and removes humidity control moulding piece, and the refrigeration is removed humidity control moulding piece and is connected with refrigeration dehumidifying module, and it derives the outside aqueduct to electrical cabinet to be connected with on the refrigeration dehumidifying module, it still is connected with the setting at the inside fan of electrical cabinet wherein to heat the ventilation control module, it still is connected with the setting adds the hotting mask on the electrical cabinet inner wall wherein to heat the ventilation control module. The problem of electrical cabinet electrical cabinet inside produce condensation is leaded to because of the difference in temperature is great is solved.